Irrigated catheter with fluid evacuation

ABSTRACT

A catheter for use with a suction source for removing excess fluid from a tissue treatment site has a catheter body, a distal section and a fluid evacuation path, where the distal section includes a multi-lumened member and at least one evacuation port, and the fluid evacuation path extends through a lumen in the multi-lumened member to provide suction communication between the suction source and the at least one evacuation port. The fluid evacuation path may also be configured for two-way flow, including distally and proximally along the catheter.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is a continuation of and claims priority to andthe benefit of U.S. patent application Ser. No. 13/679,907 filed Nov.16, 2012, issued as U.S. Pat. No. 9,358,061, the entire content of whichis incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to an electrophysiologic catheter that isparticularly useful for ablation and sensing electrical activity ofheart tissue.

BACKGROUND OF INVENTION

Electrode catheters have been in common use in medical practice for manyyears. Diagnosis and treatment of cardiac arrythmias by means ofelectrode catheters include mapping the electrical properties of hearttissue and selectively ablating cardiac tissue by application of energy.Such ablation can cease or modify the propagation of unwanted electricalsignals from one portion of the heart to another. The ablation processdestroys the unwanted electrical pathways by formation of non-conductinglesions. Various energy delivery modalities have been disclosed forforming lesions, and include use of microwave, laser and more commonly,radiofrequency energies to create conduction blocks along the cardiactissue wall.

In a two-step procedure—mapping followed by ablation—electrical activityat locations within the heart is typically sensed and measured byadvancing a catheter containing one or more electrical sensors (orelectrodes) into the heart, and acquiring data at a multiplicity oflocations. These data are then utilized to select the tissue targetareas at which ablation is to be performed.

In use, the electrode catheter is inserted into a major vein or artery,e.g., the femoral artery, and then guided into a chamber of the heart. Areference electrode is provided, generally taped to the patient's skinor provided on the ablation catheter or another catheter. Radiofrequency (RF) current is applied to the ablation electrode of thecatheter, and flows through the surrounding media, i.e., blood andtissue, toward the reference electrode. The distribution of currentdepends on the amount of electrode surface in contact with the tissue,as compared to blood which has a higher conductivity than the tissue.

Heating of the tissue occurs due to its electrical resistivity. Thetissue is heated sufficiently to cause cellular destruction in thecardiac tissue resulting in formation of a lesion within the cardiactissue which is electrically non-conductive. During this process,heating of the ablation electrode also occurs as a result of conductionfrom the heated tissue to the electrode itself. If the electrodetemperature becomes sufficiently high, possibly above 60° C., a thintransparent coating of dehydrated blood can form on the surface of theelectrode. If the temperature continues to rise, this dehydrated layerof blood can become progressively thicker resulting in blood coagulationon the electrode surface. Because dehydrated biological material has ahigher electrical resistance than tissue, impedance to the flow ofelectrical energy into the tissue also increases. If the impedanceincreases sufficiently, an impedance rise occurs and the catheter mustbe removed from the body and the tip electrode cleaned.

In a typical application of RF current, circulating blood provides somecooling of the ablation electrode. Another method is to irrigate theablation electrode, e.g., with physiologic saline at room temperature,to actively cool the ablation electrode instead of relying on the morepassive physiological cooling provided by the blood. Because thestrength of the RF current is no longer limited by the interfacetemperature, current can be increased. This results in lesions whichtend to be larger and more spherical, usually measuring about 10 to 12mm.

The clinical effectiveness of irrigating the ablation electrode isdependent upon the distribution of flow within the electrode structureand the rate of irrigation flow through the catheter. Effectiveness isachieved by reducing the overall electrode temperature and eliminatinghot spots in the ablation electrode which can initiate coagulumformation. More channels and higher flows are more effective in reducingoverall temperature and temperature variations, i.e., hot spots. Thecoolant flow rate must be balanced against the amount of fluid that canbe injected into the patient and the increased clinical load required tomonitor and possibly refill the injection devices during a procedure. Inaddition to irrigation flow during ablation, a maintenance flow,typically a lower flow rate, is required throughout the procedure toprevent backflow of blood into the coolant passages. Thus, reducingcoolant flow by utilizing it as efficiently as possible is a desirabledesign objective.

Another consideration is the ability to control the exact position andorientation of the catheter tip. This is ability is critical and largelydetermines the usefulness of the catheter. It is generally known toincorporate into electrophysiology catheters an electromagnetic (EM)tri-axis location/position sensor for determining the location of acatheter's distal end. An EM sensor in the catheter, typically near thecatheter's distal end within the distal tip, gives rise to signals thatare used to determine the position of the device relative to a frame ofreference that is fixed either externally to the body or to the heartitself. The EM sensor may be active or passive and may operate bygenerating or receiving electrical, magnetic or ultrasonic energy fieldsor other suitable forms of energy known in the art.

Where the distal tip is irrigated, fluid loading in the patient becomesa significant factor as ablation procedures can last five or six hours.Conventional irrigated tip electrodes typically operate with a flow rateof about 17 ml/minute at below about 30 watts of RF ablation energy toabout 30-50 ml/minute at about 30 watts or greater. Moreover, currentcatheters include irrigated ring electrodes further increasing the fluidload in the patient. The pericardial space can quickly begin to fillwith the irrigation fluid, such as saline, thereby limiting the amountof time the ablation catheter can be in the body and the number ofablations that can be performed due to fluid overload.

Accordingly, it is desirable that a catheter be adapted for removal ofexcess fluids by suction through fluid evacuation ports near theablating electrodes.

SUMMARY OF THE INVENTION

The present invention is directed to a catheter for use with a suctionsource for removing excess fluid from a tissue treatment site. In oneembodiment, the catheter has an elongated catheter body, a distalsection and a fluid evacuation path, where the distal section has amulti-lumened member and at least one evacuation port, and the fluidevacuation path extends through a lumen in the multi-lumened member toprovide suction communication between the suction source and the atleast one evacuation port. The one or more evacuation ports may beformed in the multi-lumened member, or it may be formed in a tipelectrode of the distal section extending distally from themulti-lumened member.

In another embodiment, the fluid evacuation path is configured fortwo-way flow, including distally and proximally along the catheter. Thecatheter is configured for operation in two modes: irrigation andevacuation. Irrigation fluid can be transported to the tissue treatmentsite and excess irrigation fluid and/or bodily fluids can be suctionedfrom the tissue treatment site and deposited in a collection chamber. Ina detailed embodiment, the catheter includes a valve having a switchadapted to allow fluid and suction communication between the fluid pathand the suction source or fluid communication between the fluid path andthe irrigation fluid source. In a more detailed embodiment, the valveprovides first, second and third connections, the first connectionadapted for communication with the suction source, the second connectionadapted for communication with the irrigation fluid source, the thirdconnection adapted for communication with the fluid path.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective of a catheter according to an embodiment of thepresent invention, in use with a suction source and a fluid collectionchamber.

FIG. 2A is a side cross-sectional view of the catheter FIG. 1, showing ajunction between a catheter body and a deflectable distal section, takenalong a first diameter.

FIG. 2B is a side cross-sectional view of the catheter of FIG. 1,showing a junction between a catheter body and a deflectable distalsection, taken a long a second diameter generally perpendicular to thefirst diameter.

FIG. 3 is a side cross-sectional view of a distal section of thecatheter of FIG. 1, taken along a diameter.

FIG. 3A is an end cross-sectional view of the distal section of FIG. 3,taken along line A-A.

FIG. 3B is a side cross-sectional view of the distal section of FIG. 3,taken along line B-B.

FIG. 4 is a perspective view of an alternate embodiment of a catheter ofthe present invention, for use with a suction source, a collectionchamber and an irrigation fluid source.

FIG. 5 is a side cross-sectional view of a distal section of thecatheter of FIG. 4.

FIG. 5A is an end cross-section view of the distal section of FIG. 5,taken along line A-A.

DETAILED DESCRIPTION OF THE INVENTION

In an embodiment of the invention, there is provided a steerablebi-directional catheter having an irrigated tip and fluid evacuationadaptations. As shown in FIGS. 1-3, catheter 10 comprises an elongatedcatheter body 12 having proximal and distal ends, a deflectable distaltip section 14 at the distal end of the catheter body 12, and a controlhandle 16 at the proximal end of the catheter body 12.

With reference to FIGS. 1 and 2A, the catheter body 12 comprises anelongated tubular construction having a single, axial or central lumen18. The catheter body 12 is flexible, i.e., bendable but withsubstantially torsional stiffness. The catheter body 12 can be of anysuitable construction and made of any suitable material. In theillustrated embodiment, the catheter body 12 has an outer wall 22 madeof a polyurethane or PEBAX. The outer wall 22 comprises an imbeddedbraided mesh of stainless steel or the like to increase torsionalstiffness of the catheter body 12 so that, when the control handle 16 isrotated, the tip section 14 of the catheter 10 will rotate in acorresponding manner.

Extending through the single lumen 18 of the catheter body 12 arecomponents, including lead wires, an irrigation tube, a firstcompression coil through which a first puller wire extends foruni-directional deflection, if not also a second compression coilthrough which a second puller wire extends for bidirectional deflection.Other components include a cable for a position sensor, thermocouplewires, and an evacuation tube. A single lumen catheter body is oftenpreferred over a multi-lumen body because it has been found that thesingle lumen body permits better tip control when rotating the catheter.The single lumen permits the components to float freely within thecatheter body. If such wires and tube were restricted within multiplelumens, they may build up energy when the handle is rotated, resultingin the catheter body having a tendency to rotate back if, for example,the handle is released, or if bent around a curve, to flip over, eitherof which are undesirable performance characteristics.

The outer diameter of the catheter body 12 is not critical, but ispreferably no more than about 8 french, more preferably 7 french.Likewise the thickness of the outer wall 22 is not critical, but is thinenough so that the central lumen 18 can accommodate the aforementionedcomponents.

The inner surface of the outer wall 22 is lined with a stiffening tube20, which can be made of any suitable material, such as polyimide ornylon. The stiffening tube 20, along with the braided outer wall 22,provides improved torsional stability while at the same time minimizingthe wall thickness of the catheter, thus maximizing the diameter of thecentral lumen 18. The outer diameter of the stiffening tube 20 is aboutthe same as or slightly smaller than the inner diameter of the outerwall 22. Polyimide tubing is presently preferred for the stiffening tube20 because it may be very thin walled while still providing very goodstiffness. This maximizes the diameter of the central lumen 18 withoutsacrificing strength and stiffness.

An embodiment of the catheter has the outer wall 22 with an outerdiameter of from about 0.090 inch to about 0.094 inch and an innerdiameter of from about 0.061 inch to about 0.065 inch and the polyimidestiffening tube 20 having an outer diameter of from about 0.060 inch toabout 0.064 inch and an inner diameter of from about 0.051 inch to about0.056 inch.

At least one puller wire 42 for deflecting the tip section 14 extendsthrough the catheter body 12. It is anchored at its proximal end to thecontrol handle 16, and anchored at its distal end in the tip section 14.The puller wire 42 is made of any suitable metal, such as stainlesssteel or Nitinol, and is preferably coated with Teflon® or the like. Thecoating imparts lubricity to the puller wire 42. The puller wire 42preferably has a diameter ranging from about 0.006 to about 0.010inches.

A compression coil 44 is situated within the catheter body 12 insurrounding relation to a respective puller wire 42. The compressioncoil 44 extends from the proximal end of the catheter body 12 to aboutthe proximal end of the tip section 14. The compression coil 44 is madeof any suitable metal, preferably stainless steel. The compression coil44 is tightly wound on itself to provide flexibility, i.e., bending, butto resist compression. The inner diameter of the compression coil 44 ispreferably slightly larger than the diameter of the puller wire 42.Teflon® coating on the puller wire 42 allows it to slide freely withinthe compression coil 44. If desired, particularly if electrode leadwires are not enclosed by a protective sheath, the outer surface of thecompression coil 44 can be covered by a flexible, non-conductive sheath39, e.g., made of polyimide tubing, to prevent contact between thecompression coil 44 and any other wires within the catheter body 12.

The compression coil 44 is anchored at its proximal end to the proximalend of the stiffening tube 20 in the catheter body 12 by glue joint (notshown) and at its distal end to the tip section 14 by glue joint 51.Both glue joints preferably comprise polyurethane glue or the like. Theglue may be applied by means of a syringe or the like through a holemade between the outer surface of the catheter body 12 and the centrallumen 18. Such a hole may be formed, for example, by a needle or thelike that punctures the outer wall 22 of the catheter body 12 and thestiffening tube 20 which is heated sufficiently to form a permanenthole. The glue is then introduced through the hole to the outer surfaceof the compression coil 44 and wicks around the outer circumference toform a glue joint about the entire circumference of the compression coil44.

With reference to FIG. 2B, the illustrated embodiment of the catheter 10has a pair of puller wires 42 for bi-directional deflection, each havinga respective compression coil 44 surrounding the puller wire from abouta proximal end of the catheter body 12 to about a distal end of thecatheter body 12.

The tip section 14 distal of the catheter body 12 carries a tipelectrode 17 and a plurality of ring electrodes 21. The tip section 14also carries an electromagnetic position sensor 46. A suitable means forattaching the catheter body 12 to the tip section 14 is illustrated inFIGS. 2A and 2B. The tip section 14 comprises a multi-lumened tubing 19,the proximal end of which comprises an outer circumferential notch 24that receives the inner surface of the outer wall 22 of the catheterbody 12. The tip section 14 and catheter body 12 are attached by glue orthe like. Before the tip section 14 and catheter body 12 are attached,however, the stiffening tube 20 is inserted into the catheter body 12.The distal end of the stiffening tube 20 is fixedly attached near thedistal end of the catheter body 12 by forming a glue joint 23 withpolyurethane glue or the like. Preferably a small distance, e.g., about3 mm, is provided between the distal end of the catheter body 12 and thedistal end of the stiffening tube 20 to permit room for the catheterbody 12 to receive the notch 24 of the tip section 14. A force isapplied to the proximal end of the stiffening tube 20, and, while thestiffening tube 20 is under compression, a first glue joint (not shown)is made between the stiffening tube 20 and the outer wall 22 by a fastdrying glue, e.g. Super Glue® Thereafter a second glue joint (not shown)is formed between the proximal ends of the stiffening tube 20 and outerwall 22 using a slower drying but more permanent glue, e.g.,polyurethane.

If desired, a spacer can be located within the catheter body 12 betweenthe distal end of the stiffening tube 20 and the proximal end of the tipsection 14. The spacer provides a transition in flexibility at thejunction of the catheter body 12 and tip section 14, which allows thisjunction to bend smoothly without folding or kinking. A catheter havingsuch a spacer is described in U.S. patent application Ser. No.08/924,616, entitled “Steerable Direct Myocardial RevascularizationCatheter”, the disclosure of which is incorporated herein by reference.

As shown in FIGS. 2A, 2B, 3A and 3B, the tubing 19 of the tip section 14has multiple lumens, e.g., three or four or more lumens. The tubing 19is made of a suitable non-toxic material that is preferably moreflexible than the catheter body 12. One construction of the tubing 19 isbraided polyurethane, i.e., polyurethane with an embedded mesh ofbraided stainless steel or the like, but the tubing 19 can comprise aplastic core, an inner plastic layer surrounding the core, a braidedstainless steel mesh surrounding the inner layer, and an outer plasticlayer surrounding the braided mesh. A suitable tubing is described inU.S. Pat. No. 6,569,114.

The outer diameter of the tip section 14, like that of the catheter body12, is preferably no greater than about 8 french, more preferably 7french. The size of the lumens is not critical. In one embodiment, thetip section 14 has an outer diameter of about 7 french (0.092 inch) andthe tubing 19 contains six lumens, including a central, on-axis lumen 30for lead wire 40T for the tip electrode 17, thermocouple wire pair 41and 45, a cable 48 for the position sensor 46. A pair of diametricallyopposed lumens 31, 32 are provided, each for a respective puller wire42. Off-axis lumen 33 is provided for lead wires 40R for the ringelectrodes 21. Off-axis lumen 34 is provided for an irrigation tubing38. At least one off-axis lumen 35 is provided for at least one fluidevacuation path provided in the catheter 10. The lumens may have adiameter of ranging between about 0.018 inch and 0.029 inch.

As shown in the embodiment of FIGS. 3 and 3B, a proximal end of the tipelectrode 17 is inserted into the distal end of the tubing 19 of the tipsection 14. The proximal end of the tip electrode 36 is notchedcircumferentially to fit inside the distal end of the tubing 19. Thenotched proximal end may be bonded to the tubing 19 by polyurethane glueor the like. The wires, cable and irrigation tube that extend into thetip electrode 17 help keep the tip electrode attached to the tip section14.

It is understood that the location and number of ring electrodes 21 mayvary as desired. The ring electrodes may be configured for uni- and/orbi-polarity as desired. The tip and ring electrodes 17, 21 can be madeof any suitable material, including platinum and/or iridium. Theelectrode lead wires 40T, 40R pass through the control handle 16, andterminate at their proximal end in an input jack (not shown) that may beplugged into an appropriate monitor (not shown). The portion of the leadwires 40T, 40R extending through the proximal end of the tip section 14,the central lumen 18 of the catheter body 12 and the control handle 16are enclosed within a protective sheath (not shown), which can be madeof any suitable material, preferably polyimide. The protective sheath isanchored at its distal end to the proximal end of the tip section 14 bygluing it in the lumens with polyurethane glue or the like.

Connection of lead wire 40T to the tip electrode 17 is accomplished, forexample, by welding a distal end of the lead wire into a blind hole 80(FIG. 3) formed in a proximal surface of the tip electrode. Connectionof lead wire 40R to a ring electrode 21 is accomplished, for example, byfirst forming a small hole 60 (FIGS. 3 and 3B) through an outer wall ofthe tubing 19 by inserting a needle through the outer wall and heatingthe needle sufficiently to form a permanent hole. The lead wire 40R isthen drawn through the hole by using a microhook or the like. The end ofthe lead wire 40R is stripped of any coating and soldered or welded tothe underside of the ring electrode 21, which is then slid into positionover the hole and fixed in place with polyurethane glue or the like.

The temperature sensing means provided in the tip section 14 may also bea thermistor such as Model No. AB6N2-GC14KA143E/37C sold byThermometrics (New Jersey). In the thermocouple however of theillustrated embodiment, the wire 41 is a number “40” copper wire, andthe wire 45 is a number “40” constantan wire, which gives support andstrength to the wire pair. The wires 41 and 45 of the wire pair areelectrically isolated from each other except at their distal ends wherethey contact and are twisted together, covered with a short piece ofplastic tubing 43, e.g., polyimide, and covered with epoxy. The plastictubing 43 is then attached in a blind hole 82 formed in the proximalsurface of the tip electrode 17, by polyurethane glue or the like. Thewires 41 and 45 extend through the lumen 30 of the tubing 19 of thedistal section 14, the central lumen 18 of the catheter body 12 and thecontrol handle 16. Proximal of the control handle, the wires areconnected to a connector (not shown) connectable to a temperaturemonitor (not shown).

A pair of puller wires 42 are provided for bi-directional deflection.Proximal ends of the puller wires are anchored in the control handle 16.The puller wires 42 extend through the control handle 16 and the centrallumen 18 of the catheter body 12 (FIG. 2A). In the tubing 19 of thedistal section 14, a first puller wire 42 extends through the lumen 31and a second puller wire extends through the diametrically oppositelumen 32 (FIG. 3A). Distal ends of the puller wires are anchored nearthe distal end of the tubing 19 into a side wall of the tubing by T-bars72 (FIG. 2B). Alternatively, a metal tubing of hypodermic stock can becrimped onto the distal end of each the puller wire 42 and solderedinside a blind hole formed in the proximal surface of the tip electrode17.

The cable 48 for the electromagnetic sensor 46 extends through the lumen30 of the tubing 19. Its distal end is connected to the sensor 46 (FIG.3) which is fixedly attached inside the lumen 30 near the tip electrode17 by polyurethane glue or the like.

The proximal end of the cable 48 extends out the proximal end of thecontrol handle 16 within an umbilical cord (not shown) to a sensorcontrol module (not shown) that houses a circuit board (not shown). Thecable 48 comprises multiple wires encased within a plastic coveredsheath. In the sensor control module, the wires of the electromagneticsensor cable 48 are connected to the circuit board which amplifies thesignal received from the electromagnetic sensor 46 and transmits it to acomputer (not shown) in a form understandable by the computer.

The proximal end of the irrigation tube 38 extends through the controlhandle 16 and terminates in a luer hub 84 or the like at a locationproximal to the control handle. In practice, fluid is injected into theirrigation tube 38 through the luer hub 84 (FIG. 1), and flows throughthe irrigation tube 38 extending through the central lumen 18 of thecatheter body 12 and the lumen 34 of the tip section 14 in fluidcommunication with a fluid passage and transverse branches 64 in the tipelectrode. Fluid thus travels into the tip electrode 17 via the fluidpassage 62 and transverse branches 64 where it exits the tip electrode17 via irrigation ports 66 provided at or near a distal end of the tipelectrode 17.

The catheter of the present invention advantageously provides a fluidevacuation path in suction communication with at least one fluidevacuation port 86 in the tip section 14. In the illustrated embodimentof FIG. 1, the catheter is adapted for use with a suction source 90 anda fluid collection chamber 92 in suction communication with each othervia a suitable suction conduit 94. The suction source 90, e.g., asuction pump or compressor, provides a vacuum or negative pressure inthe fluid collection chamber 92. Extending from the fluid collectionchamber 92 is a suction tube 96 whose proximal end is received in aconnector 98 that is mounted on a connecting port 100 of the collectionchamber 92. A distal end of the suction tube 96 is received in aconnector 102 that provides connection with a proximal end of anevacuation tube 104 which extends through the catheter and providessuction communication between the suction source 90 and the evacuationports 86.

The evacuation tube 104 extends through the control handle 16, throughthe central lumen 18 of the catheter body 12, and into the lumen 54 ofthe tip section 14. In one embodiment, the evacuation tube 104terminates a short distance distal of the junction between the catheterbody 12 and the tip section 14 although it is understood that the distalend may be located near or in the tip electrode 17. The evacuation tube104 is sized and shaped to provide a fluid- and suction-tight seal withthe lumen 54 which extends the length of the tubing 19 of the distalsection 14. Near the distal end of the tubing 19, a radial evacuationthrough-hole 108 is formed in the side wall of the tubing 19 incommunication with the evacuation port 86 to provide suctioncommunication between the lumen 54 and the evacuation port 86. In theillustrated embodiment, three ports are formed along a circumference ofthe tubing 19 between a distal-most ring electrode 21 and an adjacentring electrode 21 b. The plurality of ports along a circumference canrange between about one to six, and preferably between about three tofour

In operation, the catheter provides irrigation at the tissue ablationsite. Irrigation fluid enters the catheter via the luer hub 84 andpasses into the irrigation tubing 38 which extends through the controlhandle 16, the catheter body 12 and the distal section 14. The fluidenters the tip electrode 17 via the fluid passage 62, passes through thetransverse branches 64 and exits to outside of the tip electrode via theirrigation ports 66. Irrigation fluid, such as saline, helps cool thetip electrode during ablation so as to minimize the formation of char onthe tip electrode. To reduce fluid load on the patient, the evacuationpath 54 advantageously provided in the catheter 10 allows the suctionsource 90 to draw fluids (including irrigation fluid and other bodilyfluids) from the tissue ablation site and deposit the fluids in thecollection chamber 92 via the suction tube 96. The suction communicationand fluid communication between the evacuation tube 104 and thecollection chamber 92 is established when the suction tube 96 and theevacuation tube 104 are connected via the connector 102.

During ablation by the tip electrode and/or the ring electrodes,irrigation fluid passes through the catheter 10 from the control handle16 to the tip section 14 via irrigation tube 38 and exits the irrigationports 66 in the tip electrode 17 (and/or the ring electrodes 21 wherethey are adapted for irrigation). With the suction source 90 activated,negative pressure is created in the collection chamber 92 via suctionconduit 94 which creates suction in the suction tube 96 and theevacuation tube 104. Fluid encountered by the evacuation port(s) 86,including irrigation fluid delivered by the catheter to the ablationsite, is drawn through the evacuation port(s) 86 and the evacuation tube104 for deposit and collection in the collection chamber 92. Removal ofexcess fluid, especially irrigation fluid introduced by the catheter,decreases the risk of fluid overload thereby increasing the amount oftime the catheter can be in the body and the number of ablations thatcan be performed on the patient.

In an alternate embodiment illustrated in FIGS. 4, 5 and 5A, thecatheter has a path 254 for both irrigation and evacuation to allow thecatheter to operate between an irrigation mode and an evacuation mode.Structure of the catheter is similar in many respects to theaforementioned embodiment. An irrigation/evacuation (I/E) tubing 204extends through the control handle 16, the catheter body 12 and thedistal section 14 where its distal end is received in a lumen 234 thatis in fluid and suction communication with I/E ports 266 in the tipelectrode 17 via a fluid passage 262 and transverse branches 264. Aproximal end of the tubing 204 is connected to a valve 210, e.g., a3-way valve with luer fitting 212 and two ports, with port 214 in fluidcommunication with an infusion pump 216 providing irrigation fluid 218and port 220 in fluid and suction communication with suction tube 96.

In operation, the valve is positioned so that there is fluidcommunication between the infusion pump and the I/E tube and nocommunication between the suction source 90 and the I/E tube so that thecatheter can operate in the irrigation mode by providing irrigation atthe tissue ablation site. Irrigation fluid enters the catheter andpasses into the I/E tubing 204 which extends through the control handle16, the catheter body 12 and the distal section 14. The fluid thenenters the tip electrode 17 via the fluid passage 262, passes throughthe transverse branches 264 and exits to outside of the tip electrodevia the I/E ports 266.

To operate in the evacuation mode, the valve is switched to allow fluidand suction communication between the suction source and the I/E tubeand no communication between the infusion pump and the I/E tube. Asuction force provided by the suction source 90 draw fluids from thetissue ablation site by means of the suction conduit 94 and deposit thefluids in the collection chamber 92 via the suction tube 96.

To switch between the irrigation mode and the evacuation mode, theoperator adjusts the valve accordingly.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. It is further understood that the drawings are notnecessarily to scale. Accordingly, the foregoing description should notbe read as pertaining only to the precise structures described andillustrated in the accompanying drawings, but rather should be readconsistent with and as support to the following claims which are to havetheir fullest and fair scope.

What is claimed is:
 1. An ablation catheter for use with a suctionsource: an elongated catheter body; a distal section distal the catheterbody, the distal section comprising: a tip electrode adapted forablation and irrigation; a tubular member extending between the catheterbody and the tip electrode, the tubular member having at least first andsecond lumens; at least two ring electrodes proximal of the tipelectrode, the at least two ring electrodes comprising at least adistal-most ring electrode and an adjacent ring electrode; at least onededicated evacuation port in a sidewall of the tubular member betweenthe distal-most ring electrode and the adjacent ring electrode, the atleast one dedicated evacuation port being in suction communication withthe first lumen; at least one dedicated irrigation port in the tipelectrode in fluid communication with the second lumen; a fluidevacuation path extending at least through the catheter body and thefirst lumen, the fluid evacuation path configured to provide suctioncommunication between the suction source and the at least one dedicatedevacuation port.
 2. The catheter of claim 1, wherein the at least onededicated evacuation port comprises a plurality of dedicated evacuationports along a circumference of the tubular member between thedistal-most ring electrode and the adjacent ring electrode.
 3. Thecatheter of claim 2, wherein the at least one dedicated evacuation portcomprises one to six dedicated evacuation ports along the circumferenceof the tubular member between the distal-most ring electrode and theadjacent ring electrode.
 4. The catheter of claim 2, wherein the atleast one dedicated evacuation port comprises three to four dedicatedevacuation ports along the circumference of the tubular member betweenthe distal-most ring electrode and the adjacent ring electrode.
 5. Thecatheter of claim 2, wherein the at least one dedicated evacuation portcomprises three dedicated evacuation ports along the circumference ofthe tubular member between the distal-most ring electrode and theadjacent ring electrode.
 6. The catheter of claim 1, wherein the fluidevacuation path is defined in part by an evacuation tubing extendingthrough the catheter body, the evacuation tubing having a distal endreceived in the first lumen of the tubular member.
 7. The catheter ofclaim 1, wherein the distal section further comprises at least oneadditional evacuation port positioned between the tip electrode and thedistal-most ring electrode.
 8. The catheter of claim 1, furthercomprising an irrigation fluid path extending through the catheter bodyand the second lumen of the distal section, the irrigation fluid pathconfigured to pass fluid into the tip electrode.
 9. The catheter ofclaim 7, wherein the at least one additional evacuation port comprises aplurality of additional evacuation ports.
 10. The catheter of claim 9,wherein a sum of the at least one evacuation port and the plurality ofadditional evacuation ports ranges between about two and ten.